I've had 4 flight reviews; 1 in the UK and 3 in the US, each with a different instructor. All were very different and only one (in the US) involved even talking about charts and airspace, let alone looking at them. 2 in the US involved no real ground component at all. The 1 in the UK only involved discussing mnemonics for remembering what equipment was mandatory for what type of flying (and the flying of course).
I do know that the FAA mandates some elements of a flight review and I expect FAA-die hards will tell me I was let down by the instructors, or have broken the law, etc. but my point is that the content can and does vary quite a bit in practice. Every situation is different and in my opinion a good instructor will use common sense to tailor a flight review to the particular situation.